==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:191 [inline]
BUG: KASAN: use-after-free in task_is_descendant.part.3+0x610/0x670 security/yama/yama_lsm.c:295
Read of size 8 at addr ffff88809038ca20 by task syz-executor4/3985

CPU: 0 PID: 3985 Comm: syz-executor4 Not tainted 4.20.0+ #173
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d3/0x2c6 lib/dump_stack.c:113
 print_address_description.cold.5+0x9/0x1ff mm/kasan/report.c:187
 kasan_report.cold.6+0x1b/0x39 mm/kasan/report.c:317
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 __read_once_size include/linux/compiler.h:191 [inline]
 task_is_descendant.part.3+0x610/0x670 security/yama/yama_lsm.c:295
 task_is_descendant security/yama/yama_lsm.c:282 [inline]
 yama_ptrace_access_check+0x215/0x10fc security/yama/yama_lsm.c:371
 security_ptrace_access_check+0x54/0xb0 security/security.c:271
 __ptrace_may_access+0x564/0x950 kernel/ptrace.c:331
 ptrace_attach+0x1fa/0x640 kernel/ptrace.c:379
 __do_sys_ptrace kernel/ptrace.c:1129 [inline]
 __se_sys_ptrace kernel/ptrace.c:1109 [inline]
 __x64_sys_ptrace+0x229/0x260 kernel/ptrace.c:1109
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4579b9
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f979571fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000065
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00000000004579b9
RDX: 0000000000000000 RSI: 0000000000000c23 RDI: 0000000000000010
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f97957206d4
R13: 00000000004c42ef R14: 00000000004d7500 R15: 00000000ffffffff

Allocated by task 8196:
 save_stack+0x43/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 kasan_kmalloc+0xcb/0xd0 mm/kasan/common.c:482
 kasan_slab_alloc+0x12/0x20 mm/kasan/common.c:397
 kmem_cache_alloc_node+0x147/0x730 mm/slab.c:3631
 alloc_task_struct_node kernel/fork.c:158 [inline]
 dup_task_struct kernel/fork.c:849 [inline]
 copy_process+0x2027/0x8790 kernel/fork.c:1757
 _do_fork+0x1cb/0x11d0 kernel/fork.c:2222
 __do_sys_clone kernel/fork.c:2329 [inline]
 __se_sys_clone kernel/fork.c:2323 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2323
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
 save_stack+0x43/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
 __cache_free mm/slab.c:3485 [inline]
 kmem_cache_free+0x83/0x290 mm/slab.c:3747
 free_task_struct kernel/fork.c:163 [inline]
 free_task+0x16e/0x1f0 kernel/fork.c:462
 __put_task_struct+0x2e6/0x620 kernel/fork.c:735
 put_task_struct include/linux/sched/task.h:96 [inline]
 delayed_put_task_struct+0x2ff/0x4c0 kernel/exit.c:181
 __rcu_reclaim kernel/rcu/rcu.h:240 [inline]
 rcu_do_batch kernel/rcu/tree.c:2452 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
 rcu_process_callbacks+0xc5b/0x1600 kernel/rcu/tree.c:2754
 __do_softirq+0x30c/0xb2e kernel/softirq.c:292

The buggy address belongs to the object at ffff88809038c540
 which belongs to the cache task_struct(81:syz4) of size 6080
The buggy address is located 1248 bytes inside of
 6080-byte region [ffff88809038c540, ffff88809038dd00)
The buggy address belongs to the page:
page:ffffea000240e300 count:1 mapcount:0 mapping:ffff8880a93daa80 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0001463b08 ffffea0002402988 ffff8880a93daa80
raw: 0000000000000000 ffff88809038c540 0000000100000001 ffff88805688a440
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88805688a440

Memory state around the buggy address:
 ffff88809038c900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809038c980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809038ca00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88809038ca80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809038cb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
kobject: 'tx-0' (000000009dbf6aa4): kobject_add_internal: parent: 'queues', set: 'queues'